1. Field of the Invention
The present invention relates to a curtain control device, particularly to a curtain control device enabling the setting of the opening range of the curtain fabric and effective slow-down of the roll-up speed of each part of the curtain, so as to reduce the noise produced by the quick actuation of each part and the defective rate.
2. Brief Description of Prior Art
Referring to Japanese Patent Gazette No. 3691372 entitled as “Roll-up Curtain Speed Reduction Device”, the device has a transverse mounting frame fixed on upper edge of the window, a winding rod provided within the transverse mounting frame, a curtain fabric rolled up on the winding rod, and a stroke setting device assembled with the winding rod. When user wants to adjust the range of rolling or unrolling of the curtain fabric, the curtain fabric is pulled down so as to drive the winding rod to rotate. At the same time, the rotor of the stroke setting device assembled with the winding rod is rotated in synchronized manner, and a positioning member provided in the groove of the rotor moves along the groove of the rotor. When user pull the curtain fabric to a desired location and then release the curtain fabric in opposite direction, the positioning member in the groove of the rotor will be actuated in opposite direction in the groove of the rotor, and the positioning member is engaged in a snap-fit point such that the rotor is locked and is unable to rotate. Furthermore, the winding rod is thus also locked so that the curtain fabric rolled on the winding rod can be fixed at the desired range of rolling or unrolling. However, the rotor of the conventional stroke setting device only has a single groove, and the snap-fit point in the groove only allows a slightly downward recess so as to maintain the smooth movement of the positioning member in the groove, thus the positioning member often fails to be locked effectively in position. On the other hand, if the recessed depth at the snap-fit point is enlarged, the positioning member might be unable to escape from the snap-fit point so that effect of controlling the positioning of the curtain fabric in rolling or unrolling might become worse. Moreover, this conventional device still needs the assistance of torsion spring, which will push cost upward. Hence, there is still rooms for further improvement.